The present invention relates to a weft feeder for weaving looms comprising improved means to accumulate the weft reserve.
It is known that weaving looms using as weft insertion means a carrier other than the shuttle, namely gripper looms, projectile looms and, lastly, air and water looms, require--for a proper working--the weft to be fed therein at a low and most regular tension.
It is also known that, in order to obtain this result, devices called weft feeders, or weft presenting devices, have already been adopted since some time in said looms, said devices being positioned between the bobbin--from which the weft is picked--and the loom insertion means, and forming a weft reserve wound on a drum in the form of successive turns, the unwinding of which takes place at a practically constant tension, the value of which is furthermore adjustable, thanks to a braking system at the outlet of the drum.
The present invention concerns an interesting improvement in weft feeders of the type--since long developed and now generally preferred by loom constructors--wherein the drum around which the weft yarn winds to form the reserve is held stationary, while the turns of said reserve are laid thereon by a rotating aim and are moved forward, mutually spaced, by a set of columns prevented from rotating in respect of said drum, but partially and variably emerging from seats in its periphery, thanks to the composite motion imparted thereto by the feeder motor shaft, in respect of which they are rotatably mounted by way of a skew bushing and a bearing.
As is known to those skilled in the art, the configuration of this system--which will be better described hereinafter--does not allow the reserve of yarn turns to move forward on the drum in both rotation senses of the feeder motor shaft which controls the rotation of the winding reel, as would instead be necessary in order to operate in the twisting sense of the weft yarn being fed, if wishing to prevent--especially during unwinding--the fibres which form said yarn by twisting from falling out of order.
With the above system, in order to adapt the sense of rotation of the weft feeder to the yarn twisting sense, it is in fact necessary not only to reverse the rotation sense of the weft feeder motor, but also to provide for a true and proper disassembly by replacing parts of the mobile columns unit.
This forms a serious limitation for these devices, which need to be partially disassembled whenever the loom is being fed with an article, the yarns of which have a different twist from that of the previous article.
The object of the present invention is to provide a constructive arrangement which avoids having to carry out, in weft feeders of the aforementioned type, the above tiresome disassembly operation when having to change the type of weft yarn used for weaving, and which allows instead adapting the weft feeder to any type of weft yarn, in a simple, convenient and prompt manner, and without having to disassemble any of its parts.